Autumn migration and wintering areas of Peregrine Falcons Falco peregrinus nesting on the Kola Peninsula, northern Russia

Four female Peregrine Falcons Falco peregrinus breeding on the Kola Peninsula, Russia, were fitted with satellite-received transmitters in 1994. Their breeding home ranges averaged 1175 (sd = ±714) km², and overlapped considerably. All left their breeding grounds in September and migrated generally south-west along the Baltic Sea. The mean travel rate for three falcons was 190 km/day. Two Falcons wintered on the coasts of France and in southern Spain, which were, respectively, 2909 and 4262 km from their breeding sites. Data on migration routes suggested that Falcons took a near-direct route to the wintering areas. No prolonged stopovers were apparent. The 90% minimum convex polygon winter range of a bird that migrated to Spain encompassed 213 km² ( n  = 54). The area of the 50% minimum convex polygon was 21.5 km² ( n  = 29). Data from this study agree with others from North America that show that Falcons breeding in a single area do not necessarily follow the same migratory path southward and do not necessarily use the same wintering grounds.     

Movements by juvenile and immature Steller's Sea Eagles Haliaeetus pelagicus tracked by satellite

Twenty‐four juvenile Steller's Sea Eagles Haliaeetus pelagicus were tracked via satellite from natal areas in Magadan, Kabarovsk, Amur, Sakhalin and Kamchatka. Nestling dispersal occurred between 9 September and 6 December (n = 24), mostly 14 September–21 October, and did not differ among regions or years. Most eagles made stopovers of 4–28 days during migration. Migration occurred 9 September–18 January, mostly along previously described routes, taking 4–116 days to complete (n = 18). Eagles averaged 47.8 km/day excluding stopovers; 22.9 km/day including stopovers. The mean degrees of latitude spanned during migration was: Kamchatka, 2.1; Magadan, 11.6; Amur, 7.3; and Sakhalin, 1.1. Eagle winter range sizes varied. Eagles concentrated in 1–3 subareas within overall winter ranges. The mean size of the first wintering subareas was 274 km², the second 529 km², and the third 1181 km². Second wintering areas were south of first wintering areas. Spring migration started between 2 February and 31 March. Two eagles from Magadan were tracked onto summering grounds, well south of their natal areas. Both had early and late summering areas. One bird was followed for 25 months. It initiated its second autumn migration in the first half of October and arrived on its wintering grounds on 26 December. The second autumn migration covered 1839 km (20.9–22.4 km/day). Unlike its first winter when it used two subareas, this bird used only one subarea in 1998–99, but this was located near wintering areas used in 1997–98. It left its wintering ground between 13 April and 13 May, and arrived on its summering grounds between 7 June and 8 July. Unlike most satellite radiotracking studies, data are presented from a relatively large number of birds from across their breeding range, including new information on eagle movements on the wintering grounds and during the second year.     

Migration timing and routes,and wintering areas of Flammulated Owls

Determining patterns in annual movements of animals is an important component of population ecology, particularly for migratory birds where migration timing and routes, and wintering habitats have key bearing on population dynamics. From 2009 to 2011, we used light‐level geolocators to document the migratory movements of Flammulated Owls (Psiloscops flammeolus). Four males departed from breeding areas in Colorado for fall migration between ≤5 and 21 October, arrived in wintering areas in Mexico between 11 October and 3 November, departed from wintering areas from ≤6 to 21 April, and returned to Colorado between 15 and 21 May. Core wintering areas for three males were located in the Trans‐Mexican Volcanic Belt Mountains in the states of Jalisco, Michoacán, and Puebla in central and east‐central Mexico, and the core area for the other male was in the Sierra Madre Oriental Mountains in Tamaulipas. The mean distance from breeding to wintering centroids was 2057 ± 128 km (SE). During fall migration, two males took a southeastern path to eastern Mexico, and two males took a path due south to central Mexico. In contrast, during spring migration, all four males traveled north from Mexico along the Sierra Madre Oriental Mountains to the Rio Grande Valley and north through New Mexico. The first stopovers in fall and last stopovers in spring were the longest in duration for all males and located 300–400 km from breeding areas. Final spring stopovers may have allowed male Flammulated Owls to fine tune the timing of their return to high‐elevation breeding areas where late snows are not uncommon. One male tracked in both years had similar migration routes, timing, and wintering areas each year. Core wintering and final stopover areas were located primarily in coniferous forests and woodlands, particularly pine‐oak forests, suggesting that these are important habitats for Flammulated Owls throughout their annual cycle.     

Breeding success in a Houbara Bustard Chlamydotis [undulata] macqueenii population on the eastern fringe of the Jungar Basin, People's Republic of China

Nesting success and chick survival of a migratory population of Houbara Bustard Chlamydotis [undulata] macqueenii were studied during three consecutive years (1998–2000) in the Xinjiang province of north‐west China. A total of 45 nests was monitored and 85 broods comprising 227 chicks were captured, of which 82 chicks were radio‐tracked. Start of laying varied between 6 and 17 April between years but the laying mode fell consistently between 26 and 30 April. Mean clutch size was 4.0 (sd = 0.8) (range 2–6) for early clutches and 3.3 (sd = 1.1) for late clutches (range 2–5). The average nesting success was 0.588 (sd = 0.270) but great variations were observed between years –0.882 in 1998, 0.530 in 1999 and 0.351 in 2000. This was related to increased predation in 1999 and 2000, which is reflected by increased predator density (chiefly Corsac Fox Vulpes corsac and Long‐legged Buzzards Buteo rufinus). The overall hatchability, defined as the proportion of eggs hatched in successful nests was 0.839 sd = 0.238). The average brood size at hatching varied from 2.9 (sd = 0.8) to 3.3 (sd = 0.9) according to years, and no significant decrease in brood size was observed in the first 5 days post‐hatching. In 1999 and 2000 the brood size diminished sharply (14% and 27%, respectively) in prefledging chicks. A further severe decrease (37%) was observed in fledglings in 2000, probably due to predation by raptors. For the 3 years of the study, a successful female Houbara would bring on average 2.3 (sd = 0.9) chicks to fledging and would have lost 30.2% (sd = 14.9%) of its brood to adversity during the rearing process. The proportion of females that lost their entire brood was 0.181 in 1998, 0.708 in 1999 and 0.453 in 2000. For the 3 years of the study, only 55.3% (sd = 26.3%) of the females hatching eggs brought chicks to fledging. The overall chick production was 0.827 per breeding female per year and the probability of an egg laid producing a fledgling of 8 weeks old was 0.190.     

Comparative migration strategies of wild and captive‐bred Asian Houbara Chlamydotis macqueenii

For migratory species, the success of population reintroduction or reinforcement through captive‐bred released individuals depends on survivors undertaking appropriate migrations. We assess whether captive‐bred Asian Houbara Chlamydotis macqueenii from a breeding programme established with locally sourced individuals and released into suitable habitat during spring or summer undertake similar migrations to those of wild birds. Using satellite telemetry, we compare the migrations of 29 captive‐bred juveniles, 10 wild juveniles and 39 wild adults (including three birds first tracked as juveniles), examining migratory propensity (proportion migrating), timing, direction, stopover duration and frequency, efficiency (route deviation), and wintering and breeding season locations. Captive‐bred birds initiated autumn migration an average of 20.6 (±4.6 se) days later and wintered 470.8 km (±76.4) closer to the breeding grounds, mainly in Turkmenistan, northern Iran and Afghanistan, than wild birds, which migrated 1217.8 km (±76.4), predominantly wintering in southern Iran and Pakistan (juveniles and adults were similar). Wintering locations of four surviving captive‐bred birds were similar in subsequent years (median distance to first wintering site = 70.8 km, range 6.56–221.6 km), suggesting that individual captive‐bred birds (but not necessarily their progeny) remain faithful to their first wintering latitude. The migratory performance of captive‐bred birds was otherwise similar to that of wild juveniles. Although the long‐term fitness consequences for captive‐bred birds establishing wintering sites at the northern edge of those occupied by wild birds remain to be quantified, it is clear that the pattern of wild migrations established by long‐term selection is not replicated. If the shorter migration distance of young captive‐bred birds has a physiological rather than a genetic basis, then their progeny may still exhibit wild‐type migration. However, as there is a considerable genetic component to migration, captive breeding management must respect migratory population structure as well as natal and release‐site fidelity.     

Migratory connectivity of American woodcock derived using satellite telemetry

American woodcock (Scolopax minor; woodcock) migratory connectivity (i.e., association between breeding and wintering areas) is largely unknown, even though current woodcock management is predicated on such associations. Woodcock are currently managed in the Eastern and Central management regions in the United States with the boundary between management regions analogous to the boundary between the Atlantic and Mississippi flyways, based largely on analysis of band returns from hunters. Factors during migration influence survival and fitness, and existing data derived from banding and very high frequency telemetry provide only coarse-scale information to assess factors influencing woodcock migratory movement patterns and behavior. To assess whether current management-region boundaries correspond with woodcock migratory connectivity in the Central Management Region and to describe migration patterns with higher resolution than has been previously possible, we deployed satellite transmitters on 73 woodcock (25 adult and 28 juvenile females, and 8 adult and 12 juvenile males) and recorded 87 autumn or spring migration paths from 2014 to 2016. Marked woodcock used 2 primary migrations routes: a Western Route and a Central Route. The Western Route ran north-south, connecting the breeding and wintering grounds within the Central Management Region. The hourglass-shaped Central Route connected an area on the wintering grounds reaching from Texas to Florida, to sites throughout northeastern North America in both the Eastern Management Region and Central Management Region and woodcock following this route migrated through the area between the Appalachian Mountains and the Mississippi Alluvial Valley in western Tennessee during autumn and spring. Two of 17 woodcock captured associated with breeding areas in Michigan, Wisconsin, or Minnesota migrated to wintering sites in the Eastern Management Region and 12 marked woodcock captured on wintering areas in Texas and Louisiana migrated to breeding sites in the Eastern Management Region. Woodcock that used the Western Route exhibited high concentrations of stopovers during spring in the Arkansas Ozark Mountains and northern Missouri, and along the Mississippi River on the border between Wisconsin and Minnesota, and autumn concentrations of stopovers in southwestern Iowa, central Missouri, the Arkansas portion of the Ozark Mountains, and around the junction of Texas, Louisiana, Oklahoma, and Arkansas. Woodcock that used the Central Route exhibited high concentrations of stopovers during spring in northern Mississippi through western Tennessee, western Kentucky, and the Missouri Bootheel, and autumn concentrations of stopovers in northern Illinois, southwestern Ohio, and the portions of Kentucky and Tennessee west of the Appalachian Mountains. We suggest that current management of woodcock based on 2 management regions may not be consistent with the apparent lack of strong migratory connectivity we observed. Our results also suggest where management of migration habitat might be most beneficial to woodcock. © 2019 The Wildlife Society.     

Satellite telemetry reveals long‐distance migration in the Asian great bustard Otis tarda dybowskii

The range of the great bustard stretches 10 000 km across Eurasia, one of the largest ranges of any threatened species. While movement patterns of the western subspecies of great bustard are relatively well‐understood, this is the first research to monitor the movements of the more endangered Asian subspecies of great bustard through telemetry and to link a breeding population of Asian great bustards to their wintering grounds. Using Argos/GPS platform transmitter terminals, we identified the annual movement patterns of three female great bustards captured at their breeding sites in northern Mongolia. The 4000 km round‐trip migration we have recorded terminated at wintering grounds in Shaanxi, China. This route is twice as long as has previously been reported for great bustards, which are among the heaviest flying birds. The journey was accomplished in approximately two months each way, at ground velocities of 48–98 km h^?1, and incorporated multiple and variable stopover sites. On their wintering grounds these birds moved itinerantly across relatively large home ranges. Our findings confirm that migratory behavior in this species varies longitudinally. This variation may be attributable to longitudinal gradients in seasonality and severity of winter across Eurasia. The distance and duration of the migratory route taken by great bustards breeding in Mongolia, the crossing of an international border, the incorporation of many stopovers, and the use of a large wintering territory present challenges to the conservation of the Asian subspecies of great bustard in this rapidly changing part of the world.     

Annual Cycle and Migration Strategies of a Trans-Saharan Migratory Songbird: A Geolocator Study in the Great Reed Warbler

Recent technological advancements now allow us to obtain geographical position data for a wide range of animal movements. Here we used light-level geolocators to study the annual migration cycle in great reed warblers (Acrocephalus arundinaceus), a passerine bird breeding in Eurasia and wintering in sub-Saharan Africa. We were specifically interested in seasonal strategies in routes and schedules of migration. We found that the great reed warblers (all males, no females were included) migrated from the Swedish breeding site in early August. After spending up to three weeks at scattered stopover sites in central to south-eastern Europe, they resumed migration and crossed the Mediterranean Sea and Sahara Desert without lengthy stopovers. They then spread out over a large overwintering area and each bird utilised two (or even three) main wintering sites that were spatially separated by a distinct mid-winter movement. Spring migration initiation date differed widely between individuals (1-27 April). Several males took a more westerly route over the Sahara in spring than in autumn, and in general there were fewer long-distance travels and more frequent shorter stopovers, including one in northern Africa, in spring. The shorter stopovers made spring migration on average faster than autumn migration. There was a strong correlation between the spring departure dates from wintering sites and the arrival dates at the breeding ground. All males had a high migration speed in spring despite large variation in departure dates, indicating a time-minimization strategy to achieve an early arrival at the breeding site; the latter being decisive for high reproductive success in great reed warblers. Our results have important implications for the understanding of long-distance migrants’ ability to predict conditions at distant breeding sites and adapt to rapid environmental change.     

Foraging patterns of breeding Dolphin Gulls Larus scoresbii at Punta Tombo, Argentina

The Dolphin Gull Larus scoresbii is a little-known, rare species endemic to southern South America. Knowledge of its feeding ecology is essential for development of management and conservation strategies. To obtain information on their use of food resources and on the frequency and duration of their foraging trips, we followed seven individuals by radiotelemetry during the breeding season of 2002 at the Punta Tombo Reserve, Argentina. In 99% of mapped locations ( n  = 4069) the Gulls were within 2.4 km of their colony. Dolphin Gulls foraged mostly at the colonies of three other species, feeding on Magellanic Penguin Spheniscus magellanicus and Imperial Cormorant Phalacrocorax atriceps regurgitates and on Southern Sea Lion Otaria flavescens faeces. The sea lion colony was the most frequently visited foraging area, accounting for 64% of the total ( n  = 260 trips). A similar trend was observed during both the incubation (60%, n  = 38 trips) and the chick (64%, n  = 40 trips) stages. The mean number of trips per day was 3.8 (range = 3–5), with a mean duration of 123 min (sd = ±27). Trip duration differed between foraging areas, being significantly longer at the sea lion than at the penguin and cormorant colonies. The small foraging range given by its particular feeding strategy suggests that Dolphin Gulls, in contrast to most other seabirds that range over large expanses of ocean in search of food, may be effectively conserved within protected areas during the breeding season.     

Seasonal changes in habitat use by Houbara Bustards Chlamydotis [undulata] macqueenii in northern Saudi Arabia

Habitat preferences by Houbara Bustards Chlamydotis [undulata] macqueenii in Harrat al-Harrah reserve, in northern Saudi Arabia were determined from sightings of birds in all seasons over three years. Vegetation and crawling invertebrate abundance were sampled in each habitat. Houbara Bustards showed seasonally changing habitat preferences that appeared to be influenced primarily by vegetation phenology, abundance and cover. More densely vegetated areas (10–17% cover) were preferred. Seasonal and inter-habitat variations in invertebrate numbers were not reflected in differential habitat use by Houbara Bustards. The highest selection ratio for a single habitat (dry lakes) occurred in summer, coinciding with the fruiting of Shafallah Capparis spinosa. Selectivity of habitats was least in spring, when green vegetation was most widespread. Changes in Houbara Bustard habitat preferences in response to marked seasonal changes in habitats brought about by well-defined patterns of rainfall indicate that studies of habitat selection should consider the entire annual cycle. The importance of vegetative cover and the sensitivity of Houbara Bustards to human disturbance suggest that reserves set aside for Houbara Bustards should be extensive, diverse and largely free of livestock, human occupation and its associated disturbances.     

Comparing areas of suitable habitats along travelled and possible shortest routes in migration of White-naped Cranes Grus vipio in East Asia

Many migratory species take detours when migrating from their breeding to wintering grounds rather than following the shortest route available. To test whether the distribution of potentially suitable habitats might be a factor causing the use of less direct detours during migration, we analysed the migratory routes of five White-naped Cranes Grus vipio satellite-tracked from central–east Russia, and compared the total area of wetlands and grasslands along the migratory routes travelled by the Cranes with that along the shortest possible routes to the Cranes' wintering grounds. All five Cranes made an easterly detour, and the distance ratio of the routes used by Cranes to the shortest possible route was 1.13 ± 0.03 sd. Based on National Oceanic and Atmospheric Administration satellite images, we demonstrate that the area of wetlands and grasslands along the migration routes travelled by Cranes was greater than along the shortest possible routes.     

Individual variation in migratory movements and winter behaviour of Iberian Lesser Kestrels Falco naumanni revealed by geolocators

The population decline of the Lesser Kestrel Falco naumanni has been the subject of studies across its Western Palaearctic breeding range, but little is known about its use of pre‐migratory areas or African wintering quarters. We used geolocators to describe the temporal and spatial patterns of Portuguese Lesser Kestrel migration and wintering behaviour. Data on the complete migration were obtained from four individuals and another three provided further information. Prior to southward migration, Lesser Kestrels showed two different behaviours: northward‐orientated movements to Spain and movements in the proximity of the breeding area. Autumn migration took place mostly in late September; spring departures occurred mainly in the first half of February. Wintering grounds included Senegal, Mauritania and Mali, with individuals overlapping considerably in Senegal. Movements registered within the wintering grounds suggest itinerant behaviour in relation to local flushes of prey. During spring migration, birds crossed the Sahara Desert through Mauritania, Western Sahara and Morocco before passing over the Mediterranean to reach Portugal. Autumn migration lasted 4.8 ± 1.1 days, and spring migration lasted 4.1 ± 0.3 days. The mean daily flight range varied between approximately 300 and 850 km for an entire journey of around 2500 km. Effective protection of roosting sites in both pre‐migratory and wintering areas and maintaining grasshopper populations in Sahelian wintering quarters appear crucial in preserving this threatened migratory raptor across its African–Eurasian flyway. There was no evidence of any deleterious effects of fitting birds with loggers.     

Distribution and nesting density of the Philippine Eagle Pithecophaga jefferyi on Mindanao Island,Philippines: what do we know after 100 years?

The Philippine Eagle Pithecophaga jefferyi , first discovered in 1896, is one of the world's most endangered eagles. It has been reported primarily from only four main islands of the Philippine archipelago. We have studied it extensively for the past three decades. Using data from 1991 to 1998 as best representing the current status of the species on the island of Mindanao, we estimated the mean nearest-neighbour distances between breeding pairs, with remarkably little variation, to be 12.74 km ( n  = 13 nests plus six pairs without located nests, se = ±0.86 km, range = 8.3–17.5 km). Forest cover within circular plots based on nearest-neighbour pairs, in conjunction with estimates of remaining suitable forest habitat (approximately 14 000 km²), yield estimates of the maximum number of breeding pairs on Mindanao ranging from 82 to 233, depending on how the forest cover is factored into the estimates.     

Autumn migration of Montagu’s harriers Circus pygargus tracked by satellite telemetry

Although there is a general understanding of Montagu’s harriers migration routes and wintering areas, detailed information on the species’ migration is still lacking. However, improvements in satellite tracking technology in recent years, have enabled the study of medium-sized species by means of satellite telemetry. In 2006, ten adult Montagu’s harriers were fitted with satellite transmitters in northeastern Spain and tracked during their autumn migration to their wintering grounds in sub-Saharan Africa. The migration took between 10 and 30 days, and the end point was determined using breakpoint regressions. Whereas some birds had stopovers of more than a week, others stayed at the same site for only 1 or 2 days at the most. The tagged birds ultimately established at wintering grounds located along the border of Mauritania with Mali and Senegal, a distance of nearly 3000 km from the breeding sites. These sites are situated within a small range of latitudes (14° and 17°N), although distributed over a wider range of longitudes (−15°E and −4°E), with some birds occupying sites more than 1000 km apart. The distance covered in 1 day during the migration ranged between 93 and 219 km, with peaks of traveling speed of up to 65 km/h. Harriers were recorded traveling only during daytime, covering the longest distances in the late afternoon, suggesting that they are daytime migrants. Most of the distance was covered between 1500 and 2000 hours, and no traveling was recorded between 2000 and 0500 hours. During migration, harriers flew close to the ground (40–100 m on average). Improved knowledge of the harriers’ exact wintering sites may provide insights on the problems Montagu’s harriers face during the winter, highlighting the need to take into account what happens in both the breeding and wintering grounds to implement successful conservation measures.     

Around the Mediterranean: an extreme example of loop migration in a long‐distance migratory passerine

An important issue in migration research is how small‐bodied passerines pass over vast geographical barriers; in European–African avian migration, these are represented by the Mediterranean Sea and the Sahara Desert. Eastern (passing eastern Mediterranean), central (passing Apennine Peninsula) and western (via western Mediterranean) major migration flyways are distinguished for European migratory birds. The autumn and spring migration routes may differ (loop migration) and there could be a certain level of individual flexibility in how individuals navigate themselves during a single migration cycle. We used light‐level loggers to map migration routes of barn swallows Hirundo rustica breeding in the centre of a wide putative contact zone between the northeastern and southernwestern European populations that differ in migration flyways utilised and wintering grounds. Our data documented high variation in migration patterns and wintering sites of tracked birds (n = 19 individuals) from a single breeding colony, with evidence for loop migration in all but one of the tracked swallows. In general, two migratory strategies were distinguished. In the first, birds wintering in a belt stretching from southcentral to southern Africa that used an eastern route for both the spring and autumn migration, then shifted their spring migration eastwards (anti‐clockwise loops, n = 12). In the second, birds used an eastern or central route to their wintering grounds in central Africa, shifting the spring migration route westward (clockwise loops, n = 7). In addition, we observed an extremely wide clockwise loop migration encompassing the entire Mediterranean, with one individual utilising both the eastern (autumn) and western (spring) migratory flyway during a single annual migration cycle. Further investigation is needed to ascertain whether clockwise migratory loops encircling the entire Mediterranean also occur other small long‐distance passerine species.     

The phenology mismatch hypothesis: are declines of migrant birds linked to uneven global climate change?

1.  Migrant bird populations are declining and have been linked to anthropogenic climate change. The phenology mismatch hypothesis predicts that migrant birds, which experience a greater rate of warming in their breeding grounds compared to their wintering grounds, are more likely to be in decline, because their migration will occur later and they may then miss the early stages of the breeding season. Population trends will also be negatively correlated with distance, because the chances of phenology mismatch increase with number of staging sites.
2.  Population trends from the Palaearctic (1990–2000) and Nearctic (1980–2006) were collated for 193 spatially separate migrant bird populations, along with temperature trends for the wintering and breeding areas. An index of phenology mismatch was calculated as the difference between wintering and breeding temperature trends.
3.  In the Nearctic, phenology mismatch was correlated with population declines as predicted, but in the Palaearctic, distance was more important. This suggests that differential global climate change may be responsible for contributing to some migrant species' declines, but its effects may be more important in the Nearctic.
4.  Differences in geography and so average migration distance, migrant species composition and history of anthropogenic change in the two areas may account for the differences in the strength of the importance of phenology mismatch on migrant declines in the Nearctic and Palaearctic.     

Effects of consecutive,contrasting, winters on the bird population of an Anglesey pine plantation

Capsule European Nightjars Caprimulgus europaeus breeding in southern England were found to over-winter in the Democratic Republic of Congo.

Aims To ascertain the wintering areas and migration routes of European Nightjars breeding in southern England.

Methods The wintering areas of three Nightjars were mapped using light geolocation tags (two in 2008 and one in 2010). For one of these birds, details of the timing and route of migration were determined. The impact of the birds' behaviour on location accuracy was measured and data on the timing of emergence and roosting was collected.

Results All three Nightjars were found to be wintering in the south and east of the Democratic Republic of Congo, in an area not previously considered to be part of the wintering range of this species. The route of migration differed in each period. Autumn migration was across central Sahara, whereas in spring the route was to the west of the Sahara. Aberrations in the light curve caused by the roosting and emergence of the birds were found to affect the estimated location of the wintering areas, shifting them approximately 1° south, and reducing the estimated accuracy of the locations. The timing of these aberrations showed that roosting and emergence roughly follow the timing of dawn and dusk.

Conclusions Current distribution maps for the wintering areas of Nightjars in Africa probably under-represent the true distribution of the species in the continent. The wide dispersal of birds from the same breeding area in the UK may be an indication of mixing of breeding populations during the wintering period. Further study is needed to understand how these results fit into the larger picture of Nightjar migration both from the UK and the wider Eurasian breeding range, and to determine locations of stopovers.     

Invertebrate diet of the Houbara Bustard Chlamydotis [undulata] macqueenii in Abu Dhabi from calibrated faecal analysis

The ecology of the Houbara Bustard Chlamydotis [undulata] macqueenii is poorly known and populations are declining due to hunting and habitat loss. As wintering populations in Abu Dhabi may be limited by habitat and food, we studied the diet using calibrated faecal analysis. Prey were categorized into 16 groups and fed to captive birds under controlled conditions. We calculated the recovery rates of prey following digestion and identified consistent fragments for each group. Wild Houbara Bustard faeces were collected and examined for key fragments, and initial prey intake was calibrated. Plant remains were identified and their contribution was estimated. Fewer than 28% faeces contained >50% plant material by volume and only 12% contained 95% or more. Numerically, the most important prey were: ants (64%), large nocturnal tenebrionids (14.5%), small climbing tenebrionids (12%) and diurnal tenebrionids. However, the Tenebrionidae contributed 97% of the animal biomass. The relative proportions of prey in the diet were similar to relative abundance as assessed by pitfall trapping. Estimates of the energetic value of the prey suggested that on average Houbara Bustards must consume around 670 desert invertebrates/day to meet energy needs. The effort required to catch these prey may vary at least ten-fold seasonally. On average plants could provide a further 6.4–14% energy but more work is needed on this. Whether Houbara Bustards wintering in Abu Dhabi are prey-limited depends on prey densities and renewal rates which remain unknown.     

Winter survival of North American grassland birds is driven by weather and grassland condition in the Chihuahuan Desert

Populations of grassland birds that overwinter in the Chihuahuan Desert are declining more rapidly than other grassland birds, and survival during the non‐breeding season may have a strong influence on population trends of these species. Habitat loss and deterioration due to desertification may be contributing to these declines, and the winter ecology of grassland birds under these changing environmental conditions remains relatively unexplored. To fill this information gap, we estimated the survival of two grassland‐obligate sparrows, Baird's Sparrows (Ammodramus bairdii) and Grasshopper Sparrows (A. savannarum), on their wintering grounds in the Chihuahuan Desert, and investigated the role of habitat structure and weather on survival rates. We deployed radio‐transmitters on Baird's (N = 49) and Grasshopper (N = 126) sparrows near Janos, Chihuahua, and tracked birds from November to March during the winters of 2012–2013 and 2013–2014. Causes of mortality included avian predators, mammals, and possibly weather. We estimated an overall weekly winter survival probability of ? = 92.73% (95% CI[s] = 88.63–95.44%) for Baird's Sparrows in 2012–2013. We estimated a weekly winter survival probability of ? = 93.48% (95% CI[s] = 90.29–96.67%) and ? = 98.78% (95% CI[s] = 97.88–99.68%) for Grasshopper Sparrow in 2012–2013 and 2013–2014, respectively. Weekly winter survival was lower with colder daily minimum temperatures for both species and in areas with taller shrubs for Grasshopper Sparrows, with the shrubs potentially increasing predation risk by providing perches for Loggerhead Shrikes (Lanius ludovicianus). Our results highlight the need to maintain healthy grass structure in wintering areas to provide birds with food, protection from predators, and adequate cover from inclement weather. Our results also demonstrate that the presence of shrubs can lower winter survival, and suggest that shrub encroachment into the winter habitat of these sparrows may be an important driver of their population declines. Shrub removal could increase survival of wintering sparrows in the Chihuahuan Desert by reducing availability of perches for avian predators, thus reducing predation risk.     

Habitat preferences of the Ortolan Bunting (Emberiza hortulana) in its prime wintering grounds,the cereal-dominated Ethiopian Highlands

Agricultural intensification and land-use changes are major factors impacting farmland biodiversity. The Ortolan Bunting Emberiza hortulana is the long-distance trans-Saharan migratory passerine that has undergone the most dramatic decline among all European farmland birds. The factors responsible for this decline may originate from the breeding grounds, migration stopovers and/or overwintering quarters. Very little is known about conditions on the species' wintering grounds, but a recent study has highlighted the utmost importance of the traditionally managed agroecosystems in the Ethiopian Highlands as a key wintering area, apparently harbouring as much as 90% of the world's Ortolan Bunting population. Using radiotracking and line transect surveys, this study aimed to provide fine-grained information about species–habitat relationships in the Ortolan Bunting overwintering quarters. Our results showed the importance, at the landscape scale, of small-scale agriculture, notably of traditionally managed, cereal-dominated fields interspersed with semi-natural structures. At a foraging-site scale, on the other hand, patches of bare ground in combination with large areas of post-harvesting stubble represented key habitat features. Stubbles provide an essential food resource and bare ground promotes ground foraging by enhancing food accessibility. The maintenance of a traditional agricultural economy will be essential to maintain the habitat potential for the Ortolan Buntings overwintering in the Ethiopian Highlands and will be instrumental in preserving its world population from further decline.